Strange supernova remnant harbors Milky Way’s youngest black hole

Structure of remnant hints explosion was only known gamma ray burst in galaxy.

Composite X-ray/optical/radio image of the supernova remnant W49B. The structure and composition of this remnant hints that it was a gamma ray burst - one of the most violent explosions known - and likely harbors a black hole at its center.

While stars like our Sun go gently into that good night, stars more than 25 times more massive explode in violent supernovae. Since stars that big are rare, their explosions are too, so astronomers typically have to do forensic work on supernova remnants in our galaxy. One particular remnant is one the brightest X- and gamma-ray sources around, marking it as a relatively recent explosion. By studying the remnant, astronomers have determined it likely harbors the youngest black hole in the Milky Way, and the original explosion may have been extremely energetic.

Laura A. Lopez, Enrico Ramirez-Ruiz, Daniel Castro, and Sarah Pearson used long-exposure X-ray observations to study the remnant. They found distinct signs of a supernova with strong jets shooting from the poles. The astronomers failed to find any sign of a neutron star, meaning the supernova must have left a black hole instead. And the emissions suggest it's only 1,000 years of age, which would make the black hole the youngest known in our galaxy.

Over their lifetimes, stars fuse light atoms into slightly heavier ones, but fusing most of the elements in the periodic table requires the intense energies of a supernova. By mapping certain of these elements—iron in particular—in a supernova remnant, astronomers can recreate the conditions under which the star died.

Most supernovae are roughly spherical: the star that made them explodes more or less equally in all directions at once. This shows up in the signature of the elements produced in the explosion: if the cloud is mostly spherical, then the explosion was symmetrical. However, if the remnant is non-spherical, there are a number of potential explanations.

However, at least one significant type of supernova is inherently asymmetric. Known as a bipolar or jet-driven supernova, this type explodes energetically, with matter channeled preferentially into two jets aligned with the poles of the dying star. While stars more than 8 times the Sun's mass die in supernovae, only very massive stars—greater than 25 times the mass of the Sun—can produce bipolar supernovae, according to theory. When Earth lies in the direction of one of the jets, the supernova appears much brighter and includes many gamma rays, so it is known as a gamma ray burst.

(Gamma ray bursts have been known since the 1960s when they were spotted by spy satellites looking for illicit testing of nuclear weapons, but until fairly recently their origins were mysterious.)

The signature of such a supernova is an elongated structure running through the heart of the remnant, which can be seen via X-ray emissions from iron atoms. Another giveaway is the balance of chemical elements: in bipolar supernovas, silicon and sulfur are noticeably less abundant than they are in spherical explosions. So, to spot a bipolar supernova, astronomers need to look for several types of evidence, all of which can be gathered using detailed X-ray observations.

Supernova remnant W49B is one of the brightest in the galaxy, in terms of its X-ray and gamma ray emission. Previous observations found that the iron atoms were nearly absent from one side of the supernova, while other elements were more regularly distributed.

The authors of the present study observed W49B with the Chandra X-ray Observatory for over 60 hours, allowing a deep examination of the structure and composition of the remnant. They found the clear sign of a lane of iron atoms running through the remnant, and relative abundances of other elements consistent with a bipolar supernova—the first of its kind ever observed in the Milky Way.

Additionally, they looked for X-ray emissions from a neutron star, the dense collapsed core of a massive star produced by most supernovas. Since W49B is only about 1,000 years old, a neutron star at its heart would be very bright, but the researchers found nothing. Since there are only two possible outcomes from a supernova, the researchers concluded the other possibility must be true: W49B has a black hole at its center. If that's the case, the black hole is the youngest known in our galaxy.

The remnant is about 26,000 light-years away, so when I say it is 1,000 years old, I mean it actually happened 27,000 years ago, and its light didn't reach us immediately. A supernova so distant wouldn't have been as noticeable as, say, the Crab Nebula supernova seen in 1054 CE, which was briefly visible in daylight. However, if our ancestors had possessed gamma ray telescopes, they would have seen the only known gamma ray burst in the Milky Way's history, and had metaphorical front-row seats to one of the most violent explosions in the Universe.

How near would such a Supernova have to be to Gamma - roast us all? To me that appears to be the ultimate version of Doomsday

According to New Scientist [30 July 2005, p 13] 6,500 light years or nearer, but the Earth would need to be in the GRB beam which resembles a lighthouse beam

The wiki for GRB's says this:-"... if WR 104 were to hit Earth with a burst of 10 seconds duration, its gamma rays could deplete about 25 percent of the world's ozone layer. This would result in mass extinction, food chain depletion, and starvation. The side of Earth facing the GRB would receive potentially lethal radiation exposure, which can cause radiation sickness in the short term, and in the long term result in serious impacts to life due to ozone layer depletion"

Are there any possible links between this event and climate change at that period?

Edit: Why the down votes? I was not being sarcastic. I asked it as there was an article I read not too long ago implying that gamma rays *may* have had an effect on climate change. I was curious to know if anyone who knows about climate change could enlighten me as this event may already have been used for/against in the climate change debate.

As I have read this "light didn't reach us" comments so many time previously. It puzzled me a bit.

Do you mean our telescope didn't reach its light source immediately, and it takes the telescope several years to get its focus on its light source?

Here's my experience I encounter on a highway. We were on this highway at mid night hours. It's dark. I happened look up to the hills and enjoying the surrounding scenery and happened to noticing that houses up the hills many have its porch lights on. I can imagining they are for security reasons. I noticed the lights from its porch and lights from the windows only gets to a few feet away from the porch and where places further out between those porch lights and our vehicle was in a complete darkness. Which that tells me, the lights from the porch only get to as far as may be 20 or 30 feet away, from a single 100W light bulb?

I was thinking those porch lights have never had the chance to get to our moving vehicle. It's only our good eye visions that let us to see the porch lights a few thousand feet away from us.

Like those porch lights, the light from 26,000 light years away has never gotten to the Earth. It stopped short may be a few billion miles away from its origin?

Reason: The photon was dropped dead without any collision with other photon. The further out the photon is, the less chances to collided with other photon therefore the shorter life of a photon. Am I right or wrong?

That's not right, Evolution. Think about the term "light year." That's the distance that light can travel in one year, because light's speed is relatively fixed in space. It's not about the light being blocked by anything, it's about how fast light can travel (light speed). If something is 27,000 light years away, it would take 27,000 years for the light (traveling at "the speed of light") to get to us regardless of whatever is in the way. Photons don't just "stop" or "drop dead," they travel forever unless they're absorbed by some other type of particle and re-emitted. If there was a cloud of dust between us at the super nova remnant, the particles in the dust cloud might soak up and re-emit the photons more diffusely (i.e. in different directions from the one they came in) and keep most of the photons from reaching us, but they don't effectively slow it down. If there's nothing in the way, a photon will keep going forever. Your example with the porch light isn't a good one. The light from the porch goes out in all directions, getting fainter as it goes because the photons are radiating out to fill up an ever-increasing volume of space. That means the further you get, the less number of photons from the porch their are in any cubic meter of space around you. Also, the air acts to scatter them and deflect them away from their normal path. But they can't slow it down, and light doesn't get "tired" and stop moving. It's not that we have excellent eye sight, it's just that the further you get from a light source the fewer photons from it occupy the space around you because they've spread out as they go.

Reason: The photon was dropped dead without any collision with other photon. The further out the photon is, the less chances to collided with other photon therefore the shorter life of a photon. Am I right or wrong?

wrong. If our sun [for example] exploded now it would take 8 minutes for us on Earth to see the explosion because it takes 8 minutes for the light to reach us from that distance. When we see the explosion of the sun we have a microsecond [& then we are vaporized] to realise it really happened 8 minutes before now.

The event described in this article happened 27,000 years agoWe are 26,000 light years away from the eventOur ancestors 1,000 years ago would have seen the initial explosion if it was bright enough What we see now in our instruments is the after effect of the explosion where the material has spread out into a bubble

So, satellites saw several gamma ray bursts in the 60's but 1000 years ago our ancestors could have seen the only known gamma ray burst in history of our Milky Way. Ik can, sort of get what you mean here but would strongly suggest against colourfull expressions like this on subjects so alien to so many. It sounds really confusing.

I note that the statistics is such that we have been hit by ~10^3 GRBs during Earth history. [Wikipedia] Life takes a licking, but keeps on ticking.

Speaking of deadly astronomical events, this reminded me of yesterday's release on the putative find of the world's third largest impact zone. "An asteroid measuring up to 20km across hit South Australia up to 360 million years ago and left behind the one of the largest asteroid impact zones on Earth, according to new research published today." ""It's likely to be part of a particular cluster that was linked with a mass extinction event at that time."" [ http://phys.org/news/2013-02-world-larg ... -zone.html ]

If it happened up to ~ 360 million years ago, that could be the Hangenberg event in the Late Devonian extinction series of events. [ http://en.wikipedia.org/wiki/Late_Devonian_extinction ] Like the K-Pg impactor event, and "Unlike the [initiating] Kellwasser event, the Hangenberg event affected marine and terrestrial habitats."

That would make it the 2nd impactor that could be tied to mass extinctions, unless I am mistaken. Unlike the K-Pg event it may not have impacted unlucky regarding location (in calciferous and sulfurous sediments) but unlucky in time (after some other environmental stressor had bottlenecked diversity).

Quote:

However, if our ancestors had possessed gamma ray telescopes, they would have seen the only known gamma ray burst in the Milky Way's history, and had metaphorical front-row seats to one of the most violent explosions in the Universe.

Now the terminology gets confusing. A gamma ray burst (GRB) seems to be referring to the burst when a bipolar supernova (SN) collimated gamma ray jet hits us face on.

What would be the chances that the first identified MW bipolar SN was line-of sight? And wouldn't that decrease observability? I tried scanning the paper, it seems they don't identify the GRB direction, but that the SNR is aligning 'West to East' from our POV. Am I mistaken?

Assuming I am not mistaken, maybe our suitably accessorized ancestors would have picked up on, by necessity of the efficient jet collimation, a scattered gamma ray diffuse glow that may accompany bipolar SNs (I assume). If I get the physics and terminology correct (but again, what are the odds? =D), they would then see the GRB event but not a GRB.

Are there any possible links between this event and climate change at that period?

Edit: Why the down votes? I was not being sarcastic. I asked it as there was an article I read not too long ago implying that gamma rays *may* have had an effect on climate change. I was curious to know if anyone who knows about climate change could enlighten me as this event may already have been used for/against in the climate change debate.

Environmental effects from a GRB is certainly pertinent.

But the wild apposition of two different time scales, a short GRB and a perhaps decades long ozone layer depletion vs climate regimes that spans millenniums seems superficially like trolling. (Even AGW won't go away for some centuries, should we stop our GW gas release today.)

The other apposition, mistaking the proposed (but many times over rejected) climate effects from cosmic ray variability with gamma ray variability, is strengthening the superficial image.

Finally, there is no scientific debate over the observed AGW regime. The only ones who regularly refer to a mysterious "climate change debate" is science denialists. And this section is a science section.

It links further to a CR article with a short section on role in climate and its change. IIRC the latest papers will make the IPCC assessment stand in the next IPCC: "the most recent IPCC study disputed the mechanism,". They don't find much of an effect.

Reason: The photon was dropped dead without any collision with other photon. The further out the photon is, the less chances to collided with other photon therefore the shorter life of a photon. Am I right or wrong?

Ah, um, wow. I hope you don't take it too strongly if I note that this is Disney animation physics.

I know that a lot of people believe this is the "common sense" notion of motion, especially in US if I remember the statistics correctly. But it is totally wrong! See how an astronaut keeps traveling as he lets go of the craft under a space walk. If there is no friction, there is no "common sense" stopping.

Let us work together to decrease that deplorable statistics:

Newton's First law of motion states: "If an object experiences no net force, then its velocity is constant".

The reason these 300+ year old physics is observed is because of Nöther's theorems: preserving something in a system under change manifests as preserving a "charge". E.g. we have literary the same amount of electron charge everywhere because we have the same type EM field everywhere.

Here the laws of classical mechanics are kept under straight line motion, i.e. the system moves the same "here" as "there". It has to be that way, or the universe would be a messy place indeed, with local laws of physics and what not.

Which means the so called linear momentum is preserved as the "charge" in question. So: the object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero).

Reason: The photon was dropped dead without any collision with other photon. The further out the photon is, the less chances to collided with other photon therefore the shorter life of a photon. Am I right or wrong?

Ah, um, wow. I hope you don't take it too strongly if I note that this is Disney animation physics.

I know that a lot of people believe this is the "common sense" notion of motion, especially in US if I remember the statistics correctly. But it is totally wrong! See how an astronaut keeps traveling as he lets go of the craft under a space walk. If there is no friction, there is no "common sense" stopping.

Let us work together to decrease that deplorable statistics:

Newton's First law of motion states: "If an object experiences no net force, then its velocity is constant".

The reason these 300+ year old physics is observed is because of Nöther's theorems: preserving something in a system under change manifests as preserving a "charge". E.g. we have literary the same amount of electron charge everywhere because we have the same type EM field everywhere.

Here the laws of classical mechanics are kept under straight line motion, i.e. the system moves the same "here" as "there". It has to be that way, or the universe would be a messy place indeed, with local laws of physics and what not.

Which means the so called linear momentum is preserved as the "charge" in question. So: the object is either at rest (if its velocity is zero), or it moves in a straight line with constant speed (if its velocity is nonzero).

Interesting post in that it both precisely identified and corrected the previous poster's misapprehension and yet did so in a manner almost surely guaranteed to completely fly over the head of said poster, who's reasoning about physics is clearly based on 'common sense' personal experience (and is thus probably quite useful in most everyday experience, in fact this sort of physical reasoning is probably somewhat hardwired in humans). Not intending this as a criticism, but more of an interesting observation on the difficulty of communication between people using common sense experiential reasoning vs mathematical logical reasoning. Its pretty tricky to cross that gap (and I'm not going to try you notice .

Are there any possible links between this event and climate change at that period?

Edit: Why the down votes? I was not being sarcastic. I asked it as there was an article I read not too long ago implying that gamma rays *may* have had an effect on climate change. I was curious to know if anyone who knows about climate change could enlighten me as this event may already have been used for/against in the climate change debate.

Environmental effects from a GRB is certainly pertinent.

But the wild apposition of two different time scales, a short GRB and a perhaps decades long ozone layer depletion vs climate regimes that spans millenniums seems superficially like trolling. (Even AGW won't go away for some centuries, should we stop our GW gas release today.)

The other apposition, mistaking the proposed (but many times over rejected) climate effects from cosmic ray variability with gamma ray variability, is strengthening the superficial image.

Finally, there is no scientific debate over the observed AGW regime. The only ones who regularly refer to a mysterious "climate change debate" is science denialists. And this section is a science section.

It links further to a CR article with a short section on role in climate and its change. IIRC the latest papers will make the IPCC assessment stand in the next IPCC: "the most recent IPCC study disputed the mechanism,". They don't find much of an effect.

Thanks for the reply...I will be a bit more careful in the future as I can now see how my original post could be seen as trolling.

All ancient science and ancient physics started out with common sense questions. Why is this happening? People were wondering. Those questions were the out of the ordinary questions. We later named them "science" because of its complexity involvement. It then triggered some smart people who started looking for these complicated answers. Those were the people we later named them "scientists". As years gone by, these scientists need more tools to help them to explore more answers. Those tools were the "physics". So I don't see there is any problem to explain a common sense question through scientific ways and physics. They shared a same origin. :-)

I still having this doubt that the light from a 27,000 light years away object has the chance to reach Earth. Photon keep on going but eventually it faint out (quotes from @wheels) due to times and distances. And 27,000 light years is a great distance. I don't care if a photon live forever, it's going to drop somewhere between there and Earth. Thank you. :-)

No it's not, unless it hits something. It doesn't get fainter just from traveling. They don't get "tired." They don't slow down or lose steam or anything; unless they run into something, they have to keep moving at light speed forever.

I still having this doubt that the light from a 27,000 light years away object has the chance to reach Earth. Photon keep on going but eventually it faint out (quotes from @wheels) due to times and distances. And 27,000 light years is a great distance. I don't care if a photon live forever, it's going to drop somewhere between there and Earth. Thank you. :-)

Not to be rude, but you really don't have a good grasp of how big the universe really is, and how remarkably full of nothing it is. There really isn't a whole lot of stuff in the galaxy between us and this remnant. You may think that 27,000 light years is very far away, but next to the size of the universe, it's peanuts. If you think that something relatively local to us in our own galaxy has a high chance for absorption of all photons coming from it, how do you think that we can see other galaxies millions of light years away from us?

If there's a black hole in its centre, isn't it sucking up the supernova remnant ( granted if it's within its event horizon ) and shouldn't the preclude the birth of any new stars? Just curious. And another question: Does the Supernova explosion happen in an instant? The ejection of matter from the Neutron Star when it's torn apart? I really just cannot imagine how it happens.

If there's a black hole in its centre, isn't it sucking up the supernova remnant ( granted if it's within its event horizon ) and shouldn't the preclude the birth of any new stars? Just curious. And another question: Does the Supernova explosion happen in an instant? The ejection of matter from the Neutron Star when it's torn apart? I really just cannot imagine how it happens.

A black hole does not automatically suck up everything around it. Just like satellites can orbit the earth, outside of a few tens of kilometers from a star-sized black hole, matter can orbit a black hole without falling in. The event horizon lies about 25 km from a standard star-sized black hole. This is the space from which light that falls in cannot escape.

For comparison, the smallest pixel in that image at the distance to the supernova is roughly 8000 times the distance between the earth and the sun, or 1.2 billion km (give or take an arithmetic error).

At the center of this supernova remnant, there is not likely to be much matter to fall in. The explosion cleared out a relatively large part of space. Everything you see in the picture as a supernova remnant are either stars that were nowhere near the explosion, or matter ejected from the explosion that is pushing yet more interstellar matter out of the way.

As for how long this type of supernova takes, the energy is produced in a fraction of a second when the core of a massive collapses. The process is even hard for scientists to imagine. Unless something has changed in the last couple years that I missed, there is still debate as to what causes the collapsing core to produce an explosion. It probably has something to do with shocks or, if a gamma-ray burst occurs, magnetic fields. Things like Kavli Prizes and MacArthur Genius Grants are waiting for those who can really figure this out.

The reason these 300+ year old physics is observed is because of Nöther's theorems: preserving something in a system under change manifests as preserving a "charge". E.g. we have literary the same amount of electron charge everywhere because we have the same type EM field everywhere.

Torb's I think you mean literally, not literary. The second term meaning "relating to literature"